A recent experiment [L. De Marco, G. Valtolina, K. Matsuda, W. G. Tobias, J. P. Covey, and J. Ye, A degenerate Fermi gas of polar molecules, Science 363, 853 (2019)] reported for the first time the preparation of a Fermi degenerate gas of polar molecules and observed a suppression of their chemical reaction rate compared to the one expected from a treatment assuming classical Maxwell-Boltzmann statistics. While it was hypothesized that the suppression in the ultracold regime had its roots in the Fermi statistics of the molecules, this argument is inconsistent with the fact that the Fermi pressure should set a lower bound for the chemical reaction rate. Here we develop a simple model of chemical reactions that occur via the formation and decay of molecular complexes. We indeed find that pure two-body molecule losses are unable to explain the observed suppression. Instead we extend our description beyond two-body physics by including multibody complex-molecule interactions. Although our model is able to quantitatively reproduce recent experimental observations, it requires parameters physically unlikely for direct microscopic interactions. The underlying processes, however, might emerge effectively from many-body or medium effects. A detailed understanding of the direct microscopic mechanisms responsible for these higher-order interaction processes is therefore still pending.
BT - Physical Review A DA - 2020-12 DO - 10.1103/PhysRevA.102.063322 IS - 6 N2 -A recent experiment [L. De Marco, G. Valtolina, K. Matsuda, W. G. Tobias, J. P. Covey, and J. Ye, A degenerate Fermi gas of polar molecules, Science 363, 853 (2019)] reported for the first time the preparation of a Fermi degenerate gas of polar molecules and observed a suppression of their chemical reaction rate compared to the one expected from a treatment assuming classical Maxwell-Boltzmann statistics. While it was hypothesized that the suppression in the ultracold regime had its roots in the Fermi statistics of the molecules, this argument is inconsistent with the fact that the Fermi pressure should set a lower bound for the chemical reaction rate. Here we develop a simple model of chemical reactions that occur via the formation and decay of molecular complexes. We indeed find that pure two-body molecule losses are unable to explain the observed suppression. Instead we extend our description beyond two-body physics by including multibody complex-molecule interactions. Although our model is able to quantitatively reproduce recent experimental observations, it requires parameters physically unlikely for direct microscopic interactions. The underlying processes, however, might emerge effectively from many-body or medium effects. A detailed understanding of the direct microscopic mechanisms responsible for these higher-order interaction processes is therefore still pending.
PY - 2020 SE - 063322 EP - 063322 T2 - Physical Review A TI - Exploring chemical reactions in a quantum degenerate gas of polar molecules via complex formation UR - https://journals.aps.org/pra/pdf/10.1103/PhysRevA.102.063322 VL - 102 ER -